Haematopoietic Stem Cell Transplant Journey
In an autologous transplant, patient's own stem cells are used for infusion.
In an allogeneic transplant, a donor's stem cells are used for infusion. The donor can be a relative of the patient (e.g. sibling or parent) or unrelated (e.g. volunteer donors from local or overseas donor registries, unrelated umbilical cord blood).
During the pre-transplant conference, the doctor will share the following information in detail:- Reasons for offering them the option of a transplant- Entire process of transplantation- Risks of transplantation- Short and long term effects of their transplant
Patients and their caregivers will have the opportunity to ask questions and clarify concerns regarding the transplant. Patients will be asked to sign a consent form when they agree to proceed with transplantation.
Pre-transplant investigations and procedures
Patient will undergo a series of tests to determine if they can proceed with the transplant procedure.
They will also see a dentist a few weeks before their planned transplant admission to ensure that any potential source of oral infection can be treated before admission.
A thin flexible tubing (central venous catheter) will be inserted in the patients' neck or chest to allow for all infusions and blood taking to be done. The catheter usually remains in place for the duration of the patients' treatment to minimise needle punctures to their veins.
A dietician will assess patients' nutritional status and needs and will advise patients on nutrition through the different phases of the transplant.
Conditioning therapy involves administration of chemotherapy drugs, sometimes in combination with whole body radiation therapy.
It is done for the following reasons:
- Destroy any remaining cancerous cells in patients' body- For allogeneic haematopoietic stem cell transplants, it weakens patients' immune system so that it does not destroy their donor's stem cells- Destroy diseased or damaged bone marrow and make room for the healthy stem cells to grow
Collection of donor cells (Allogeneic Haematopoietic Stem Cell Transplant)
Donor stem cells will be collected the day before or on the day of patients' transplant. Donors generally have a choice of donating either bone marrow or peripheral blood stem cells (PBSCs).
If the donor chooses to donate bone marrow, he/she will have a general anaesthetic and have approximately one litre of bone marrow extracted from his/her pelvis. The product may then be filtered and may undergo processing when it arrives before it is infused into the patient.
Donors who choose to donate PBSCs will have 4 days of G-CSF injections before the blood stem cells are collected on the 5th and possibly 6th days. Collection in this case is via a process called "leukapheresis", which takes about 4-6 hours to complete. Blood is taken out of the body into a machine, the stem cells are collected, and then the blood is immediately returned.
Other stem cell sources include patients' own frozen stem cells or frozen umbilical cord blood units. Frozen umbilical cord blood units will arrive in patients' hospital before they commence conditioning and will be kept frozen until immediately before the infusion.
Stem cell transfusion usually takes place 48 to 72 hours after the completion of conditioning.
Patients may be given intravenous hydration and pre-medication to reduce any side-effects and discomfort.
Patients are given the stem cells through their central line. The infusion is similar to a blood transfusion and will be monitored closely by a doctor and nurse.
The stem cell bags will be flushed with saline to remove any remaining stem cells from the bags and the infusion tubing. Patients will be monitored hourly for the next 6 hours and 4 hours thereafter.
Some side effects which patients may experience include allergic reactions like rash or urticaria, chills, rigor, fever, hypotension, tachycardia and breathlessness. Other commonly reported side effects are nausea, flushing and abdominal pain.
They may also be experiencing a variety of side effects from the conditioning therapy, such as:- Mouth sores or ulcers- Nausea and vomiting- Diarrhoea- Constipation- Altered taste and smell- Tiredness and lethargy- Fluid gain- Weight loss- Veno-occlusive disease (VOD)- Anaemia
Waiting for engraftment
After transplantation, patients' neutrophil, platelet and red cell production will be low for a period of time. Engraftment is when the new blood-forming cells start to grow and make healthy blood stem cells that show up in patients' blood.
Patients' neutrophil count will start to rise in 14 to 21 days after the infusion, and platelet counts a few days later.
During this period, patients will be hospitalised for close monitoring and treatment.
Post-discharge from Hospital
Following discharge, patients will be followed up closely at the Haematology Centre, at least twice a week for several months. It may take 6 to 12 months for patients to regain their energy levels and resume normal activities.
It is important that patients contact their doctor for advice immediately if they are feeling unwell.
After discharge, patients will be prescribed with medication such as immunosuppressive drugs and drugs to reduce risk of infections.
Herbal remedies, traditional medicines and health supplements should not be taken without first consulting the transplant physician.
After discharge, patients may continue to experience side effects which may affect their appetite and sense of taste or smell.
Post-discharge follow up appointments with their dietician will be arranged to reassess their nutritional status.
Patients are encouraged to do light exercises regularly. However, exercising in public areas or swimming is not recommended if white blood cell or platelet counts are low. If in doubt, patients should consult their doctor.
1. What are the benefits of a Haematopoietic Stem Cell Transplant?
- An autologous transplant allows patients to undergo a more intensive chemotherapy to control their cancer. An allogeneic transplant gives patients a new and healthy set of stem cells to replace the cancerous ones and a fully functioning immune system.
2. What is the process of finding a donor?
- Tissue typingA sample of blood or a buccal swab is required in order to determine the patients' tissue type, known as the Human Leukocyte Antigen (HLA) typing.
- Sibling donorsSiblings refer to brothers or sisters from the same biological parents. Each biological sibling of the patient has a 25% chance of being fully compatible.
- Volunteer unrelated donorsThese are donors who have registered themselves with their local bone marrow donor registry. The registry will then perform tissue typing and match them with the recipients.
- Unrelated cord bloodUmbilical cord blood units are collected from the placenta following birth. These stem cells are then frozen and stored in cord blood banks. Public cord blood banks provide donated units for unrelated cord blood transplants.
- Haplo-identical donorsHaplo-identical donors are donors who are a 50% HLA match with the patients. Examples include the patients' biological parents, some siblings and their children.
3. What are the types of Conditioning?
- In an autologous transplant, this usually refers to the use of "myeloablative conditioning" followed by the infusion of patients' own frozen stem cells. This is only suitable for certain diseases.
- Myeloablative transplantA "myeloablative" transplant uses very high doses of chemotherapy and radiotherapy in the conditioning regime. In theory, if no stem cells are given after this treatment, patients' blood counts will never recover-hence the term "ablative". This type of conditioning gives the best immediate control of patients' disease, but has the most side effects. It is generally reserved for younger medically-fit patients who are able to withstand the side effects of the treatment.
- Non-myeloablative conditioned transplantA "non-myeloablative" conditioning transplant uses low doses of chemotherapy and/or radiotherapy. The effect of the conditioning treatment is to suppress patients' immune system so that they do not reject the donor cells. In theory, if patients do not receive any donor cells after conditioning, their own bone marrow will eventually recover.
- The conditioning has little activity against their disease, so there is a higher risk of relapse after the transplant. The immediate side effects from this form of transplant are usually mild to moderate in severity and most patients who are medically-fit enough will tolerate the treatment well. This form of conditioning may be suitable for patients as old as 70 years old.
- Reduced-intensity conditioned (mini) transplantA "reduced-intensity" conditioned transplant uses conditioning which is about midway in strength between a "myeloablative" and "non-myeloablative" transplant. The immediate side effects are again between those of a "myeloablative" and "non-myeloablative" conditioned transplant.
- The risk of relapse following this type of transplant is higher than "myeloablative" transplant, but studies have shown that the ultimate success rates in groups of patients are very similar to those who have had "myeloablative" transplant. This type of transplant conditioning may be used in patients up to about 70 years old.
4. What is the survival rate after a transplant?
- At SGH, adults receiving transplants for Acute Myeloid Leukaemia (AML) experience an overall survival of approximately 55% at 2 years. For Acute Lymphoblastic Leukaemia (ALL) this is approximately 54%, and following autologous transplants for myeloma, this is approximately 87% at 2 years. These are comparable to those reported by major centres internationally.
- At KKH, the outcome for Acute Lymphoblastic leukaemia (ALL) has climbed steadily from 40% in the 1980's to 60% in the 1990's and 80% in 2000's. Present chemotherapy regime produces a five-year overall survival and event-free survival of 92% and 82%. The survival rates for allogeneic haematopoietic stem cell transplant stands at 68%. The results are comparable to the best centres in the world.
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